RFR (M) 8225048: Shenandoah x86_32 support

[Roman Kennke]

>>>> The changes look good to me. Thanks!!
>>>
>>> Thanks! Split out test changes as JDK-8225111, so this patch does only x86_32 parts:
>>>   http://cr.openjdk.java.net/~shade/8225048/webrev.01/
>>>
>>> Still passes hotspot_gc_shenandoah.
>>
>> It's still got plenty of test changes in it.
> 
> Dang, wrong link! Here:
>  http://cr.openjdk.java.net/~shade/8225048/webrev.02/

This is much cuter indeed :-) Good!

Roman